Since we have got all this data wouldn't it be great if we could somehow use it to track our work hours?

Tracking work hours has never been easier. All you need to do is just select time and write a few words about what you did during that time.

To select time you can just drag on the timelines (hold down left mouse button while moving the mouse).
Alternately you can also check checkboxes in the details part.

Once you have selected some time click on the Add tag button.
A dialog will pop up where you can write your tags. Tags are just words which best describe your actions during that time. So for example you could write: Client X, Project X, Activity 1

By separating tags with comma you can later see reports for each tag, for example just for Client X. This means that figuring out how much time you spent working for Client X is just as easy as seeing statistics for this tag.